There are many devices for administering powdered medicaments to the lungs, which employ propellants, such as compressed gases, e.g. air, or liquefied gas propellants, to dispense and disperse the medicament. There are also a number of known breath actuated inhalation devices for administering powdered medicaments to the lungs, which have mouthpieces through which the medicament is inhaled. British Patent Specification Nos. 1 521 000, 1 520 062, 1 472 650 and 1 502 150 disclose more complex devices in which a complete capsule is inserted into the device thus ensuring no spillage of medicament prior to inhalation, and access to the medicament is gained by piercing the capsule or cutting it in half, inside the dispensing device. On inhalation the air flows into or through the capsule and the powder within is released into the air stream and flows towards the mouth.
U.S. Pat. No. 4,210,140 discloses a device in which access to the powdered medicament is gained by pulling the halves of the capsule apart so that the medicament is emptied to a suitable position for entrainment in the airflow caused by inhalation.
U.S. Pat. No. 6,655,381 relates to a pre-metered dose assembly for consistently supplying precise doses of medicament for a breath-actuated dry powder inhaler. The assembly includes a cap defining a dry powder delivery passageway for providing air to a dry powder supply port of a swirl chamber of a breath-actuated dry powder inhaler, and a magazine including a plurality of reservoirs for holding pre-metered doses of dry powder. One of the magazine and the cap is movable with respect to the other of the magazine and the cap for sequentially positioning the reservoirs within the delivery passageway of the cap. A breath-induced low pressure at an outlet port of the inhaler causes an air flow through the dry powder delivery passageway of the assembly and into the dry powder supply port that entrains dry powder from the reservoir positioned in the passageway for inhalation by a patient using the inhaler. The passageway is provided with a venturi in the passageway by the reservoir to create a flow through the reservoir and bring the powder there from.
In spite of the numerous prior art devices it would be desirable to provide a simple yet efficient administering of powdered medicaments into the alveolar region of the lungs. Indeed, it would be desirable to be enable the medicament powder to be efficiently deaggregated before being administered into the alveolar region of the lungs. In addition to the above mentioned methods of enabling deaggregation in the prior art, there exist various ways of enabling deaggregation by vibrating, shaking or providing alternative obstacles in the flow passage etc. It is common to strive for a deaggregation that makes a significant amount of the powder particles to be in accordance with a desired size and weight. This is often referred to as classifying of the powder particles. These prior art deaggregation devices may result in contamination of the downstream flow passage since medicament powder may accumulate in the downstream region of the device e.g. by certain alternative obstacles. It is of course desirable to reduce or avoid the risk of administering an inaccurate amount of medicament powder. Thus, a general reduction of powder retention within the device is desirable.